ATM connection band control method and control system

ABSTRACT

An asynchronous transfer mode (ATM) connection band control system in an ATM network may include a memory to store band acquiring data associated with one or more preferential switched virtual connections (SVCs) having high preference in the ATM network. The band acquiring data may include band data for preliminarily acquiring a band for the one or more preferential SVCs. The ATM connection band control system may also include a control portion to perform connection admission control such that a band for one of the preferential SVCs with band acquiring data in the memory is guaranteed regardless of whether a connection for the one of the preferential SVCs is established, and the band for the one of the preferential SVCs is available to a non-preferential SVC when the connection for the one of the preferential SVCs is not established.

RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.09/760,781 filed Jan. 17, 2001, now U.S. Pat. No. 6,914,904 thedisclosure of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to an asynchronous transfer mode(ATM) connection band control method and a control system. Moreparticularly, the invention relates to an ATM connection band controlmethod and a system effectively using connection bands which respectiveATM circuit ports have.

2. Description of the Related Art

In FIG. 9, the conventional ATM connection band control system includesan input circuit 1, an input buffer control portion 2 c, an ATM switchcontrol portion 3 c and an output buffer control portion 4.

The input buffer control portion 2 c includes a buffer accumulationmemory 21 c for accumulating input cells before feeding to an ATMswitch, an input buffer function portion 22 c performing writing controlof ATM cells to a buffer accumulation memory and queue management of thebuffer, a usage parameter control (UPC) portion 23 c monitoring whethera traffic of a user in communication exceeds a band declared uponswitched virtual connection (SVC) setting demand or not, a connectionadmission control (CAC) portion 24 c controlling whether a demand is tobe admitted or not upon reception of signaling of connection settingdemand for new SVC of constant bit rate (CBR), a real time variable bitrate (rt-VBR), a non-real time variable bit rate (nrt-VBR), a buffercontrol memory 26 c storing parameter or data necessary for operation ofthe input buffer function portion 22 c and the usage parameter control(UPC) portion 23 c, and a circuit interface control portion 20 cinterfacing the input buffer function portion 22 c and the input circuit1 for feeding the input cell to the ATM switch.

The ATM switch control portion 3 c includes an ATM switch 30 cperforming switching of the ATM cell, CPU 31 c performing centralcontrol process of overall system and a main memory 32 c for residenceof operation program or data necessary for operation of CPU 31 c.

FIG. 10 is a detailed block diagram showing a buffer control memory 26 crelating to the connection band of SVC of FIG. 9 and its peripheralcontrol portion. The buffer control memory 26 c includes a memory 261 cstoring band data per declared connection upon SVC setting demandnecessary for control operation of the usage parameter control (UPC)portion 23 c, a memory 263 c storing connection band data of SVC of CBR,rt-VBR, nrt-VBR, and a memory 264 c for storing data necessary for otherconnection admission control, such as available band of ATM circuit portand so forth.

Only connection band data of SVC of currently established connection ispresent in the buffer control memory 26 c for performing connectionadmission control and connection band control.

In this case, the connection band control and the connection admissioncontrol is performed for acquiring necessary connection band infirst-come-first-set order without considering connection band ofpreferential SVC when the SVC of established connection issues settingdemand. Therefore, when connection of the preferential SVC is not yetestablished and issue setting demand for connection later, the SVCsetting demand is not always admitted and can be rejected until thenecessary band is released in certain remaining band of the ATM circuitport.

On the other hand, even when the connection of the preferential SVC isestablished, if the preferential SVC is deleted once, the connectionband acquired unconditionally is released. Therefore, even when thepreferential SVC issues setting demand again, there is not guarantee toacquire connection band. If other SVC sets the connection earlier, thesetting demand may be rejected until the necessary band is released incertain remaining band of the ATM circuit port.

In the foregoing conventional ATM band control method, the first problemis that, in acquiring of the connection bands of each SVC of the CBR,rt-VBR, nrt-VBR requiring fixed band, the connection admission control(CAC) performing control on the basis of the band information of thoseactually established connection to acquire the band for thoseestablished connection at earlier timing for finite connection bands ofeach ATM circuit port. However, judgment is not made whether acquiringof band has to be done preferentially or not.

The second problem is that there is not means for preliminarilyregistering data for setting the band of the connection to bepreferentially assigned without actually establishing connection andmaking judgment upon establishing connection.

The third problem is that when connection for SVC having high preference(preferential SVC) among SVCs is temporarily released for some hindranceto open the band, if the preferential SVC is recovered from hindranceand the preferential SVC demands resetting of connection and connectionsetting demand for other SVC having low preference (non-preferentialSVC) is done at earlier timing, since connection setting of thenon-preferential SVC is performed normally, there is no guarantee forpermitting resetting of the preferential SVC. Therefore, whetherresetting of connection is successful or not simply depends on remainingband of the ATM circuit port.

On the other hand, the fourth problem is that there is no means forperforming control for ensuring and guaranteeing resetting of connectionband for the preferential SVC when the connection band of the SVC havinghigh preference, such as CBR or the like is temporarily deleted and theband is opened, and when the connection setting demand is issued byother SVC having lower preference while the connection of thepreferential SVC is deleted. The connection band is inherently acquiredin order to demanding of setting irrespective of preferential order.Therefore, for the SVC having high preference while not used constantly,connection has to be maintained irrespective whether the connection isused for communication or not to constantly occupy the connection band.

The fifth problem is that even when the SVC having high preferenceactually occupies the connection band constantly, the band may be usedfor the SVC of ATM category service which does not require fixed band,such as available bit rate (ABR), unspecified bit rate (UBR) and soforth as long as not cell flows in the connection. However, in the priorart, even when the connection is not actually used, an idle data istransmitted in CBR, the band acquired by CBR may not be released unlessthe setting of connection is actually deleted.

SUMMARY OF THE INVENTION

The present invention has been worked out for solving the problems asset forth above.

According to the first aspect of the present invention, an asynchronoustransfer mode connection band control method in a system fortransmitting and receiving an asynchronous transfer mode cell using anasynchronous transfer mode network, comprises:

first step of preliminarily setting a connection band as band acquiringdata for preferential switched virtual connection having high preferencein the asynchronous transfer mode network among connections of anasynchronous transfer mode service categories requiring a fixed band, ofconstant bit rate, in which a traffic is generated at a constantinterval in the switched virtual connection via the asynchronoustransfer mode network, and a real time variable bit rate or non-realtime variable bit rate generating a variable traffic having burstcharacteristics in transmission rate, such as variable rate video orpublic network frame relay service; and

second step of controlling the connection band including the bandacquiring data for enabling cooperation with a connection admissioncontrol for the constant bit rate, the real time asynchronous transfermode and the real time variable bit rate and the non real-time variablebit rate, and performing reception control under a condition where theband for the preferential switched virtual connection is constantlyacquired, with controlling the connection band in a range where a bandfor the preferential switched virtual connection is constantly acquiredand guaranteed, a band for a non-preferential switched virtualconnection can be constantly acquired upon the connection admissioncontrol for the non-preferential switched virtual connection.

In the preferred embodiment, it is preferred that in the first step, theconnection band of the constant bit rate, the real time variable bitrate and the non-real time switched virtual connection, is preliminarilyset and stored in a buffer control memory irrespective whether aconnection of the preferential switched virtual connection isestablished or not, and in the second step, control is performed withtaking the preliminarily set band acquiring data and data necessary forthe connection admission control of other connection including theconnection band of the switched virtual connection used currently anddata necessary for connection admission control.

In the second step, upon reception of a signal for setting demand of newswitched virtual connection from a calling terminal, judgment may bemade whether the switched virtual connection is the preferentialswitched virtual connection having high preference and having band beingacquired.

In the second step, when the new switched virtual connection settingdemand from the calling terminal is for a non-preferential switchedvirtual connection, connection band may be controlled within a rangewhere the band of the preferential switched virtual connection iscertainly maintained irrespective whether the connection of thepreferential switched virtual connection, for which the band is alreadyreserved, is established or not by cooperation of a connection receptioncontrol processing portion and a connection band controller.

In the second step, when the new switched virtual connection from thecalling terminal is the preferential switched virtual connection, forwhich band has already been reserved, connection admission may becontrolled under a condition where a band of the preferential switchedvirtual connection within a range where the band of the preferentialswitched virtual connection is certainly maintained.

Data of connection band of the preferential switched virtual connectionof the constant bit rate, the real time variable bit rate and thenon-real time variable bit rate is set irrespective whether theconnection for the switched virtual connection is established or not,and for the preferential switched virtual connection, connectionadmission control and connection band control may be performed forconstantly acquiring the band.

According to the second aspect of the present invention, an asynchronoustransfer mode connection band control system in a system fortransmitting and receiving an asynchronous transfer mode cell utilizingan asynchronous transfer mode network, comprises:

data storage means for storing a connection band of a preferentialswitched virtual connection having high preference in the asynchronoustransfer mode network being stored preliminarily as a band acquiringdata and storing acquired band data of a switched virtual connectioncurrently established connection; and

connection band control means for performing control of connection bandon the basis of a total number of bands derived by a sum of the bandacquiring data and the acquired band data stored in the data storagemeans.

According to the third aspect of the present invention, an asynchronoustransfer mode connection band control method in a method fortransmitting and receiving an asynchronous transfer mode cell utilizingan asynchronous transfer mode network, comprises:

providing data storage means for storing a connection band of apreferential switched virtual connection having high preference in theasynchronous transfer mode network being stored preliminarily as an bandacquiring data and storing acquired band data of a switched virtualconnection currently established connection; and

connection band control step of performing control of connection band onthe basis of a total number of bands derived by a sum of the bandacquiring data and the acquired band data stored in the data storagemeans.

In the preferred construction, the connection band control means or theconnection band control step may add the band acquiring data of theconnection band of the switched virtual connection when setting demandfor acquiring the connection band for the switched virtual connection isissued and the demand is admitted.

The connection band control means or the connection band control stepmay transfer the connection band data of demanded switched virtualconnection from the band acquiring data to the acquired band data whenthe switched virtual connection setting demand is issued and theswitched virtual connection for which setting demand is issued is thepreferential switched virtual connection, for which band data ispreliminarily acquired.

The connection band control means or connection band control step maymake judgment whether the switched virtual connection setting demand isto be admitted or not on the basis of a total number of bands derived bya sum of the current band acquiring data and the acquired band data whenthe switched virtual connection setting demand is issued and theswitched virtual connection for which setting demand is issued, is notthe preferential switched virtual connection, for which band data ispreliminarily acquired.

The connection band control means or connection band control step mayadd the connection band data of the switched virtual connection in theacquired band data when the switched virtual connection setting demandis admitted.

The connection band control means or connection band control step maytransfer the connection band data of the switched virtual connectionfrom the acquired band data to the band acquiring data when a switchedvirtual connection deletion demand is issued and the switched virtualconnection is the preferential switched virtual connection for which theband data is preliminarily acquired.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be understood more fully from the detaileddescription given hereinafter and from the accompanying drawings of thepreferred embodiment of the present invention, which, however, shouldnot be taken to be limitative to the invention, but are for explanationand understanding only.

In the drawings:

FIG. 1 is a schematic block diagram of the preferred embodiment of anATM connection band control system according to the present invention;

FIG. 2 is a detailed block diagram of the major part of the firstembodiment of the ATM connection band control system according to thepresent invention;

FIG. 3 is a flowchart showing operation of the first embodiment of theATM connection band control system according to the invention;

FIG. 4 is a flowchart showing operation of the first embodiment of theATM connection band control system according to the invention;

FIG. 5 is a flowchart showing operation of the first embodiment of theATM connection band control system according to the invention;

FIG. 6 is a block diagram of the major part of the second embodiment ofthe ATM connection band control system according to the presentinvention;

FIG. 7 is a block diagram of the major part of the third embodiment ofthe ATM connection band control system according to the presentinvention;

FIG. 8 is a block diagram of the major part of the fourth embodiment ofthe ATM connection band control system according to the presentinvention;

FIG. 9 is a block diagram showing the conventional ATM connection bandcontrol system; and

FIG. 10 is a detailed block diagram showing a part of the prior art.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The present invention will be discussed hereinafter in detail in termsof the preferred embodiment of the present invention with reference tothe accompanying drawings. In the following description, numerousspecific details are set forth in order to provide a thoroughunderstanding of the present invention. It will be obvious, however, tothose skilled in the art that the present invention may be practicedwithout these specific detailed. In the other instance, well-knownstructures are not shown in detail in order to avoid unnecessaryobscurity of the present invention.

FIG. 1 is a block diagram showing the first embodiment of an ATMconnection band control system according to the present invention. Theshown embodiment of the ATM connection band control system includes aninput circuit 1, an input buffer control portion 2, an ATM switchcontrol portion 3 and an output buffer control portion 4.

The input buffer control portion 2 includes a buffer accumulation memory21 for accumulating an input cell before feeding an ATM switch, an inputbuffer function portion 22 performing queue management of a controlbuffer for writing an ATM cell in the buffer accumulation memory 21, ausage parameter control (UPC) portion 23 monitoring whether a traffic ofthe user in communication exceeds a band declared upon demanding settingof SVC or not, a connection admission control (CAC) portion 24controlling whether a demand is to be admitted or not upon reception ofsignaling of connection setting demand for new SVC of CBR connectiongenerating a traffic at a predetermined interval via an ATM network froma calling terminal, such as voice, rt-VBR connection or nrt-VBR havingvariable traffic, in which a transmission rate has burst property, suchas variable rate video or a public network frame relay service, aconnection band controller 25 performing management or judgment controlof connection band data of SVC required for control operation of theconnection admission control (CAC) portion 24 and data necessary forother connection admission control such as available band of the ATMcircuit port and so forth, buffer control memory 26 for storingparameters and data necessary for operation of the input buffer functionportion 22, the usage parameter control (UPC) portion 23, the connectionadmission controller (CAC) portion 24 and the connection band controller25, and the interface control portion 20 for interfacing between theinput buffer function portion 22 for feeding the input cell to the ATMswitch and the input circuit 1.

It should be noted that the connection admission controller (CAC) is acontrol whether the demand is to be admitted upon receiving signaling ofdemand of connection setting for the SVC of CBR, rt-VBR and nrt-VBR ofATM service category requiring fixed band, and is a control heldinoperative upon receiving signaling of demand of connection setting forthe SVC of ABR or UBR in another ATM service category.

The ATM switch control portion 3 includes an ATM switch 30 performingswitching of ATM cell, CPU 31 performing central control process ofoverall system and a main memory for residence of operation program anddata necessary for operation of CPU 31. FIG. 2 is a block diagramshowing the buffer control memory 26 relating to the connection band ofthe SVC and peripheral control portion.

The buffer control memory 26, as data structure in the memory 25 storingthe buffer control memory data, includes a memory 261 storing a banddata per connection declared upon SVC setting demand necessary forcontrol operation of the usage parameter control (UPC) portion 23, amemory 262 storing band data to preliminarily acquire connection band ofthe preferential SVC necessary for control operation of the connectionband controller 25, a memory 263 storing connection band data of the SVCof CBR, rt-VBR and nrt-VBR established current connection, and a memory264 storing data necessary for connection admission control, such asavailable band and so forth of ATM circuit port.

Next, operation of the shown embodiment will be discussed with referenceto the drawings. SVC setting demand signaling for establishingconnection of the SVC received from the ATM network is fed to the inputbuffer control portion 2 from the input circuit 1 of FIG. 1 similarly toATM cell.

At this time, in the input buffer control portion 2, the judgment andcontrol whether the writing and reading in and from the bufferaccumulation and the new SVC setting demand by the connection admissioncontrol portion 24 are to be accepted or not are performed.

Next, operations of the connection admission control portion 24, theconnection band controller 25, the buffer control memory 26 and theusage parameter control portion 23 in FIGS. 1 and 2 will be discussedwith reference to FIGS. 3 and 4. In operational flowchart for acquiringconnection band of FIG. 3, upon occurrence of setting demand foracquiring connection band for the SVC, content of setting demand of theSVC is checked at step S101. Thereafter, at step S102, judgment is madewhether the SVC in question is the setting demand for acquiring theconnection band of the preferential SVC preliminarily acquired band datapresenting in the memory 262 which stores the band acquiring data ofFIG. 2.

A criterion for making judgment whether the SVC, for which setting isdemanded, is the preferential SVC, for which the band data ispreliminarily acquired, or not, can be made by data which the SVCinherently have upon establishing connection, or a combination of aplurality of data.

As inherent data which the SVC should have upon establishment ofconnection, there are a virtual path identifier (VPI) value, a virtualchannel identifier (VCI) value, an input and output port (number) of theSVC of CBR, rt-VBR, nrt-VBR, ABR, UBR and so forth, and a peak cell rate(PCR), a sustainable cell rate (SCR), a maximum burst size (MBS) astraffic parameter defined at an ATM Forum Traffic ManagementSpecification Version 4.0 (af-tm-0056.000, April, 1996: hereinafterreferred to as “TM4.0”) and so forth. By one of these or a combinationof a plurality of data, the SVC is specified to make judgment whetherthe setting demanded SVC is the preferential SVC, for which the banddata is preliminarily acquired, or not.

When the setting demanded SVC is the preferential SVC, for which theband data is preliminarily acquired, a process for guarding doubleregistration to the memory 262 storing the connection band acquiringdata of FIG. 2 is performed by the connection band controller 25 (S103)to terminate the process for connection band acquiring.

On the other hand, when the setting demanded SVC is not the preferentialSVC, for which the band data is preliminarily acquired, a total bandnumber derived by a sum of the current band acquiring data stored in thememory 262 and the acquired band data stored in the memory 263 iscalculated as a band acquiring judgment reference data (S104). On thebasis of the band acquiring judgment reference data and data necessaryfor other CAC, judgment whether setting demand for acquiring connectionband of SVC is admitted or not, is made by the connection bandcontroller 25 (S105).

When judgment is made that the setting demand for connection bandacquiring can be admitted in the judgment whether the setting demand ofthe connection band acquiring of SVC (S106) is accepted or not, processis performed to add the connection band of the SVC to be acquired in thememory 262 storing the band acquiring data in the connection bandcontroller 25 (S107).

On the other hand, at step S106, when judgment is made that the settingdemand of connection band acquiring cannot be admitted, for the settingdemand of connection band acquiring of SVC, rejection is notified(S108). Then, process for acquiring connection band is terminated.

In operational flowchart of the connection admission control of FIG. 4,upon occurrence of SVC setting demand S201, the content of the settingdemand of SVC is checked to make judgment whether the SVC in question isthe preferential SVC already acquired the band data presenting in thememory 262 which stores the band acquiring data of FIG. 2, at step S202.As criterion for making judgment whether the SVC setting demand is theconnection setting demand of the preferential SVC, for which the banddata is already acquired, or not, the judgment can be made by data whichthe SVC inherently have upon establishing connection, or a combinationof a plurality of data similarly to step S102 of FIG. 3. By specifyingthe SVC, judgment is made whether the setting demanded SVC is thepreferential SVC which has been acquired preliminarily or not.

Since the SVC is the preferential SVC which has been acquired theconnection band via the operation flow including judgment of settingshown in FIG. 3, the result of judgment at step S202 indicates that theSVC setting demand can be admitted when the SVC for which setting isdemanded is the preferential SVC for which the band data is acquiredpreliminarily (S203). Accordingly, the process for transferring thedemanded connection band data from the memory 262 which stores bandacquiring data to the memory 263 storing the acquired band data, isperformed by the connection band controller 25 (S204). Then, to theconnection admission control portion 24, execution of the acceptableprocess for the SVC setting demand is notified (S209)

On the other hand, if the SVC for which setting is demanded is not thepreferential SVC preliminarily acquired the band data, the total bandnumber is derived from the sum of the content of the memory 262 storingthe band acquiring data and the content of the memory 263 storing theacquired band data, as the band admission judgment reference data(S205). Then, on the basis of the band admission judgment reference dataand data necessary for other CAC, judgment is made whether the SVCsetting demand is to be admitted or not by the connection bandcontroller 25 (S206).

By the judgment whether the SVC setting demand is to be admitted or not(S207), if the SVC setting demand is judged as acceptable, process isperformed in the connection band controller 25 for adding the connectionband data of the demanded SVC in the memory 263 storing the acquiredband data (S208). Then, similarly to the case where the SVC for whichsetting is demanded at step S202 is the preferential SVC for which theband data is preliminarily acquired, execution of the admission processfor the SVC setting demand is notified to the connection admissioncontrol portion 24.

After notification of admission process at S209, the band data perconnection declared upon SVC setting demand is registered in the memory261 which stores the band data per connection, by the connectionadmission control portion 24 (S210). On the other hand, by makingjudgment whether the SVC setting demand is to be admitted or not at stepS207, rejection of admission for the SVC setting demand is notified tothe connection admission control portion 24 (S211). Then, the process ofaccepting connection of the SVC is terminated.

In an operational flowchart of connection deletion control of FIG. 5,upon occurrence of SVC setting deletion demand at step S301, the SVC tobe deleted is checked. At step S302, judgment is made whether the SVC inquestion is the preferential SVC already acquired the band data in thememory which stores the band acquiring data of FIG. 2, or not. Here, ascriterion for making judgment whether the connection setting demand ofthe preferential SVC, for which the band data is already acquired, thejudgment can be made by data which the SVC inherently have uponestablishing connection, or a combination of a plurality of datasimilarly to step S102 of FIG. 3. By specifying the SVC, judgment ismade whether the setting demanded SVC is the preferential SVC which hasbeen acquired preliminarily.

Since the SVC is the preferential SVC which has been acquired theconnection band via the operation flow including judgment of settingshown in FIG. 3, the result of judgment at step S302 indicates that theSVC for which deleting is demanded is the preferential SVC for which theband data is acquired preliminarily, the process for transferring thedemanded connection band data from the memory 263 which stores acquiredband data to the memory 262 storing the band acquiring data, isperformed by the connection band controller 25 (S303). Then, process forthe SVC setting deletion demand is executed to delete the connectionband data declared upon demanding SVC setting from the memory 261 whichstores the band data per connection (S304). Then, a process for deletingsetting of SVC is terminated.

On the other hand, the result of judgment at step 302 indicates that theSCV for which deleting is demanded is not the preferential SVC for whichthe band data is acquired preliminarily, the process for deleting thedeleted connection band data from the memory 263 which stores acquiredband data, is performed by the connection band controller 25 (S305).Then, process for the SVC setting deletion demand is executed to deletethe connection band data declared upon demanding SVC setting from thememory 261 which stores the band data per connection (S304). Then, aprocess for deleting setting of SVC is terminated, as the result ofjudgment as step 302 indicates that the SVC for which deleting isdemanded is the preferential SVC for which the band data is acquiredpreliminarily.

Next, discussion will be given for the second embodiment of the ATMconnection band control system according to the present invention. Inthe shown embodiment illustrated in FIG. 6, the usage parameter control(UPC) portion 23 and the memory 261 storing the band data per connectiondeclared upon SVC setting demanding performs control and function forsetting and deleting connection of the SVC. On the other hand, theconnection admission control (CAC) portion 24 and a memory 764 storingdata necessary for other CAC, such as available band of the ATM circuitport, perform setting and deletion of connection of SVC of CBR, rt-VBRand nrt-VBR. Concerning a memory 762 storing connection band data to bepreliminarily set as band acquiring data of the connection band, amemory 763 storing the connection band data of CBR, rt-VBR and nrt-VBRwhich has already been established connection, and the connection bandcontroller 25 which controls these connections are performed not onlyfor the SVC but also for permanent virtual circuit (PVC).

Concerning the permanent virtual connection (PVC), similarly to theconnection band control of SVC, the memory 762 storing the band datapreliminarily acquiring the connection band of the connection havinghigh preference (hereinafter referred to as “preferential connection”)irrespective of PVC, SVC for connection, such as CBR, rt-VBR, nrt-VBR ofATM service category requiring fixed band having values of a programclock reference (PCR), SCR, MBS defined in T.M4.0, the memory 763storing the band data of the preferential connection currentlyestablished, and a memory 260A storing data necessary for otherconnection admission such as available band of the ATM circuit port areformed to enable preliminarily set the band acquiring data necessary forpreferential connection irrespective either PVC or SVC. Also, concerningSVC, cooperation with the connection admission control is possible.

By connection band control including the band acquiring data in theconnection band controller 25 irrespective of PVC, SVC, the connectionband having low preference, for which constantly acquiring andguaranteeing the band is not required, is controlled within a rangewhere band for the preferential connection is constantly acquired andguaranteed when the connection band for non-preferential connection isto be controlled. For the preferential connection, control of band ofthe preferential connection including admission control of thepreferential SVC among the preferential connection is performed, forwhich the band is constantly acquired and guaranteed irrespectivewhether the connection of the preferential SVC is established or not.Thus, finite connection bands of each ATM circuit port can be usedefficiently.

Next, discussion will be given for the third embodiment of the ATMconnection band control system with reference to the drawings. In FIG.7, the shown embodiment is differentiated from the ATM switch controlportion in the embodiment shown in FIG. 2 in that a connection settingcontrol portion 733 is provided in an ATM switch control portion 3A. Theconnection setting control portion 733 controls setting of connection ofthe preferential SVC, for which the required band is preliminarily setas the band acquiring data.

By this, since the band required for the preferential SVC is constantlyacquired and guaranteed, the preferential SVC can be set and deleted asrequired by the connection setting control portion 733. For theconnection of the SVC of ABR or UBR which does not require the fixedband and is not controlled by the connection admission control (CAC)portion 24 and the connection band controller 25, when the preferentialSVC is unnecessary, namely when connection for the preferential SVC isnot established, the band reserved for the preferential SVC is availablefor the SVC of ABR or UBR. Thus, the finite connection band of each ATMcircuit port can be effectively used. On the other hand, when thepreferential SVC becomes necessary, namely, when the connection for thepreferential SVC is to be established, the band for the preferential SVCis acquired cutting into the band for the SVC of the ABR or UBR.Therefore, even when setting of connection for the preferential SVC isestablished later, communication of the preferential SVC can beestablished normally.

Next, discussion will be given for the fourth embodiment of the ATMconnection band control system according to the present invention withreference to FIG. 8. The shown embodiment is differentiated from the ATMswitch control portion 3 in the first embodiment shown in FIG. 2, inthat a connection-setting portion 833 of an ATM switch control portion3B is provided. Also, a memory 762 for storing band acquiring data ofthe preferential connection in a buffer control memory 26B and a memory763 storing acquired band data of PVC or SVC are differentiated from thememory 262 storing the band acquiring data of the preferential SVC andthe memory 263 storing the acquired band data of SVC.

The connection-setting control portion 833 of FIG. 8 controls setting ofthe preferential connection, for which the band required irrespective ofPVC or SVC is preliminarily set as the band acquiring data.

By this, since the band necessary for the preferential connection isconstantly acquired and guarantee, the preferential connectionirrespective of PVC or SVC can be set and deleted as required by theconnection-setting control portion 833. For the connection of the SVC ofABR or UBR which does not require the fixed band and is not controlledby the connection admission control (CAC) portion 24 and the connectionband controller 25, when the preferential SVC is unnecessary, namelywhen connection for the preferential SVC is not established, the bandreserved for the preferential SVC is available for the SVC of ABR orUBR. Thus, the finite connection band of each ATM circuit port can beeffectively used.

On the other hand, when the preferential SVC becomes necessary, namely,when the connection for the preferential SVC is to be established, theband for the preferential SVC is acquired cutting into the band for theSVC of the ABR or UBR. Therefore, even when setting of connection forthe preferential SVC is established later, communication of thepreferential SVC can be established normally.

As set forth above, by cooperating the connection band control and theconnection setting control, the band for the preferential connection canbe constantly and certainly acquired and guaranteed for the preferentialconnection. Also, for the connection of ABR or UBR which does notrequire preferential connection or when the preferential connection isnot established, the band becomes open to the ABR or UBR to permiteffective use of finite number of connection bands in each ATM circuitport.

On the other hand, by managing the connection setting control by aschedule or the like, the necessary band is used for establishingconnection only in a time zone which requires preferential connection,and in the time zone where the preferential connection is not required,control for temporarily deleting connection is performed in theconnection setting control. The connection setting control is alsocooperated with the connection band control, during the period where thepreferential connection is temporarily deleted, the connection settingdemand for the connection requiring the fixed band is not admitted, andfor the connection which does not require the fixed band, the band isopened to more effectively use the finite connection bands of each ATMcircuit port.

As set forth above, in the shown embodiment, by preliminarily settingthe connection band for the preferential SVC in the ATM network as theband acquiring data to perform connection band control including theband acquiring data, and by cooperating with the connection admissioncontrol, during connection admission control for the SVC which has lowpreference and reservation of the bans is unnecessary, the band for thepreferential SVC can be certainly acquired and guaranteed. On the otherhand, at the same time, for the preferential SVC, connection bandcontrol including the connection admission control can be realized underthe condition where the band for the preferential SVC is constantlyacquired and guaranteed irrespective whether the connection is currentlyestablished or not to more effectively use the finite connection bandsof each ATM circuit port.

For example, for the connection of the SVC having high preference(preferential SVC), even when established connection is temporarilybroken by certain failure to open the band, the connection admissioncontrol is realized in the condition where the connection band of thepreferential SVC is certainly acquired and guaranteed, for theconnection setting demand of the SVC of low preference which connectionof the preferential SVC is held broken. Furthermore, even when theconnection setting demand of the preferential SVC is issued the acquiredand guaranteed bans is again demanded to ensure establishment ofconnection again.

As set forth above, in accordance with the present invention, the firsteffect is capability of connection band control in a range where theband for the SVC of high preference and being set the bandpreliminarily, is acquired and guaranteed constantly upon connectionadmission control for the SVC of low preference and acquiring of theband being not required, by preliminarily setting the connection band ofthe SVC having high preference (i.e. preferential SVC) which is one ofCBR, rt-VBR or the nrt-VBR requiring fixed band, and by performingconnection band control with as band acquiring.

The second effect is that, with the band setting for the SVC having highpreference as set forth in the first embodiment, upon connectionadmission control for the SVC which does not require reservation ofcontrol, and by performing connection band control in the range wherethe band for the SVC for which the band is reserved is constantlyacquired and guaranteed, for the SVC of high preference, connection bandcontrol including connection admission control can be performed underthe condition where the band for the SVC of high preference isconstantly acquired and guaranteed irrespective whether the connectionof the preferential SVC is established or not.

Although the present invention has been illustrated and described withrespect to exemplary embodiment thereof, it should be understood bythose skilled in the art that the foregoing and various other changes,omission and additions may be made therein and thereto, withoutdeparting from the spirit and scope of the present invention. Therefore,the present invention should not be understood as limited to thespecific embodiment set out above but to include all possibleembodiments which can be embodied within a scope encompassed andequivalent thereof with respect to the feature set out in the appendedclaims.

1. An asynchronous transfer mode (ATM) connection band control system inan ATM network, comprising: a memory to store band acquiring dataassociated with one or more preferential switched virtual connections(SVCs) having high preference in the ATM network, the band acquiringdata including band data for preliminarily acquiring a band for the oneor more preferential SVCs; and a control portion to perform connectionadmission control such that a band for one of the preferential SVCs withband acquiring data in the memory is constantly acquired and guaranteedregardless of whether a connection for the one of the preferential SVCsis established.
 2. The ATM connection band control system of claim 1,wherein the control portion is further configured to permit anon-preferential SVC to use the band that is constantly acquired andguaranteed for the one of the preferential SVCs when a connection forthe one of the preferential SVCs is not established.
 3. The ATMconnection band control system of claim 2, wherein the control portionis further configured to acquire at least some of the band from thenon-preferential SVC when a connection for the one of the preferentialSVCs is to be established.
 4. The ATM connection band control system ofclaim 1, wherein a schedule identifies a time period during which aconnection for the one of the preferential SVCs is to be established. 5.The ATM connection band control system of claim 4, wherein theconnection for the one of the preferential SVCs is temporarily deletedoutside the time period identified by the schedule.
 6. The ATMconnection band control system of claim 5, wherein the control portionis further configured to permit a non-preferential SVC to use the bandfor the one of the preferential SVCs when the connection for the one ofthe preferential SVCs is temporarily deleted.
 7. The ATM connection bandcontrol system of claim 1, wherein the control portion is furtherconfigured to: determine when an established connection for the one ofthe preferential SVCs is broken, and permit a non-preferential SVC touse the band for the one of the preferential SVCs when the establishedconnection for the one of the preferential SVCs is broken.
 8. The ATMconnection band control system of claim 1, wherein the one or morepreferential SVCs include one or more SVCs that require a fixed band. 9.The ATM connection band control system of claim 8, wherein the one ormore preferential SVCs include one or more SVCs of a constant bit ratein which traffic is generated at a constant rate or one or more SVCs ofa real time variable bit rate or a non-real time variable bit rate inwhich traffic is generated with burst characteristics in transmissionrate.
 10. The ATM connection band control system of claim 1, wherein thecontrol portion is further configured to perform connection admissioncontrol for a requesting preferential SVC that is not one of thepreferential SVCs with band acquiring data in the memory by determiningwhether to admit the requesting preferential SVC based on the bandacquiring data in the memory.
 11. The ATM connection band control systemof claim 10, wherein the memory is further configured to store bandacquired data associated with one or more preferential SVCs that havecurrently established connections.
 12. The ATM connection band controlsystem of claim 11, wherein the control portion is configured todetermine whether to admit the requesting preferential SVC based on boththe band acquiring data and the band acquired data.
 13. The ATMconnection band control system of claim 1, wherein the control portionis further configured to perform connection admission control for one ormore permanent virtual connections (PVCs).
 14. An asynchronous transfermode (ATM) connection band control system in an ATM network, comprising:a memory to store band acquiring data and band acquired data associatedwith a plurality of preferential switched virtual connections (SVCs)having high preference in the ATM network, the band acquiring dataincluding band data for preliminarily acquiring a band for a first oneor more of the preferential SVCs, the band acquired data including banddata for a band acquired for a second one or more of the preferentialSVCs that have currently established connections; and a control portionto determine whether to admit a preferential SVC that is not one of thefirst or second preferential SVCs based on the band acquiring data andthe band acquired data.
 15. An asynchronous transfer mode (ATM)connection band control system in an ATM network, comprising: a memoryto store band acquiring data associated with one or more preferentialswitched virtual connections (SVCs) having high preference in the ATMnetwork, the band acquiring data including band data for preliminarilyacquiring a band for the one or more preferential SVCs; and a controlportion to perform connection admission control such that a band for oneof the preferential SVCs with band acquiring data in the memory isguaranteed regardless of whether a connection for the one of thepreferential SVCs is established and the band for the one of thepreferential SVCs is available to a non-preferential SVC when theconnection for the one of the preferential SVCs is not established. 16.The ATM connection band control system of claim 15, wherein the controlportion is further configured to acquire at least some of the band fromthe non-preferential SVC when a connection for the one of thepreferential SVCs is to be established and the non-preferential SVC isusing at least a portion of the band.
 17. The ATM connection bandcontrol system of claim 15, wherein a schedule identifies a time periodduring which a connection for the one of the preferential SVCs is to beestablished.
 18. The ATM connection band control system of claim 17,wherein the connection for the one of the preferential SVCs istemporarily deleted outside the time period identified by the schedule.19. The ATM connection band control system of claim 18, wherein thecontrol portion is further configured to permit the non-preferential SVCto use the band for the one of the preferential SVCs when the connectionfor the one of the preferential SVCs is temporarily deleted.
 20. The ATMconnection band control system of claim 15, wherein the control portionis further configured to: determine when an established connection forthe one of the preferential SVCs is broken, and permit thenon-preferential SVC to use the band for the one of the preferentialSVCs while the established connection for the one of the preferentialSVCs is broken.
 21. The ATM connection band control system of claim 15,wherein the control portion is further configured to perform connectionadmission control for a requesting preferential SVC that is not one ofthe preferential SVCs with band acquiring data in the memory bydetermining whether to admit the requesting preferential SVC based onthe band acquiring data in the memory.
 22. The ATM connection bandcontrol system of claim 21, wherein the memory is further configured tostore band acquired data associated with one or more preferential SVCsthat have currently established connections.
 23. The ATM connection bandcontrol system of claim 22, wherein the control portion is configured todetermine whether to admit the requesting preferential SVC based on boththe band acquiring data and the band acquired data.
 24. The ATMconnection band control system of claim 15, wherein the control portionis further configured to perform connection admission control for one ormore permanent virtual connections (PVCs).
 25. An asynchronous transfermode (ATM) connection band control method performed in an ATM network,comprising: storing band acquiring data associated with one or morepreferential switched virtual connections (SVCs) having high preferencein the ATM network, the band acquiring data including band data forpreliminarily acquiring a band for the one or more preferential SVCs;guaranteeing a band for one of the preferential SVCs with band acquiringdata in the memory regardless of whether a connection for the one of thepreferential SVCs is established; and permitting a non-preferential SVCto use the band for the one of the preferential SVCs when the connectionfor the one of the preferential SVCs is not established.
 26. Anasynchronous transfer mode (ATM) connection band control system in anATM network, comprising: means for storing band acquiring dataassociated with a plurality of first preferential switched virtualconnections (SVCs) having high preference in the ATM network, the bandacquiring data including band data for preliminarily acquiring a bandfor the first preferential SVCs; means for storing band acquired dataassociated with a plurality of second preferential SVCs having highpreference in the ATM network, the band acquired data including banddata for a band acquired for the second preferential SVCs that havecurrently established connections; and means for determining whether toadmit a preferential SVC that is not one of the first or secondpreferential SVCs based on the band acquiring data and the band acquireddata.